Breast Density

That study was all over the national news tonight.  Here's a link to the abstract of the journal article:  http://jnci.oxfordjournals.org/cgi/content/abstract/djp018

This is what the abstract says: 

"Background: It is uncertain whether evidence supports routinely estimating a postmenopausal woman's risk of breast cancer and intervening to reduce risk.

Methods: We systematically reviewed prospective studies about models and sex hormone levels to assess breast cancer risk and used meta-analysis with random effects models to summarize the predictive accuracy of breast density. We also reviewed prospective studies of the effects of exercise, weight management, healthy diet, moderate alcohol consumption, and fruit and vegetable intake on breast cancer risk, and used random effects models for a meta-analysis of tamoxifen and raloxifene for primary prevention of breast cancer. All studies reviewed were published before June 2008, and all statistical tests were two-sided.

Results: Risk models that are based on demographic characteristics and medical history had modest discriminatory accuracy for estimating breast cancer risk (c-statistics range = 0.58 - 0.63). Breast density was strongly associated with breast cancer (relative risk [RR] = 4.03, 95% confidence interval [CI] = 3.10 to 5.26, for Breast Imaging Reporting and Data System category IV vs. category I; RR = 4.20, 95% CI = 3.61 to 4.89, for >75% vs <5% of dense area), and adding breast density to models improved discriminatory accuracy (c-statistics range = 0.63 - 0.66). Estradiol was also associated with breast cancer (RR range = 2.0 - 2.9, comparing the highest vs lowest quintile of estradiol, P < .01). Most studies found that exercise, weight reduction, low-fat diet, and reduced alcohol intake were associated with a decreased risk of breast cancer. Tamoxifen and raloxifene reduced the risk of estrogen receptor-positive invasive breast cancer and invasive breast cancer overall.

Conclusions: Evidence from this study supports screening for breast cancer risk in all postmenopausal women by use of risk factors and breast density and considering chemoprevention for those found to be at high risk. Several lifestyle changes with the potential to prevent breast cancer should be recommended regardless of risk."

The journal editors noted these limitations to the study:  "The studies reviewed had diverse designs, diverse populations with different degrees of risk, and diverse methods of analyzing and expressing data, which precluded reporting the results about benefits and harms as absolute rates. Studies on lifestyle changes to reduce risk are generally observational and rely on recall."

Nevertheless, this is just one more piece of evidence supporting the argument that breast density needs to be taken into account officially when estimating the risk of BC or recurrence.  BTW, emanresu, you said this:  "I do believe that breast density is a factor, does that mean the mammorgrams cannot detect the cancer or does it allude to something about the dense breast having more estrogen."

Both are true.  Dense breast tissue is harder to examine with mammography, because it's difficult for the radiologist to see the changes and even the calcifications that might be indicative of a tumor.  Also, though, dense breast tissue is "different" from fatty tissue; and dense breast tissue has a higher risk of developing malignant tumors in the first place.  Some researchers think the cells in the dense tissue have a higher content of the enzyme "aromatase", and might be making more estrogen.

otter